In recent years, mobile terminals such as a mobile phone and PDA have become widely used, and thus communication services such as a telephone conversation and TV phone while the user is moving have become popular. However, a mobile terminal is reduced in size and weight for portability, and thus is often disadvantageous in functionality and operability compared to a stationary terminal such as a PC. For this reason, the user communicates using his or her own mobile terminal while moving, and desires to continue the same communication using a nearby stationary terminal while not moving.
A technique to satisfy this demand is described in Japanese Patent Unexamined Publication No. 2003-304251. FIG. 14 illustrates a conventional method for terminal switching described in the publication.
In FIG. 14, mobile terminal (PDA) 121 held by the user first detects nearby terminal (PC) 122 using short-distance wireless to automatically acquire the network address of this nearby terminal (PC) 122. Then, the mobile terminal (PDA) 121, as a transfer-source terminal, transfers the application-level communication session being performed with communication-destination terminal (PC) 300 to nearby terminal (PC) 122 as a transfer-destination terminal.
Meanwhile, another technique for terminal switching has been known conventionally. That is, a mobile terminal searches with short-distance wireless for a nearby terminal having a function for performing the same content of communication as that currently being performed by the user, from among plural nearby terminals, to determine a terminal to be a transfer destination, for terminal switching (refer to Support for Personal and Service Mobility in Ubiquitous Computing Environments written by K. El-Khatib and two others, Euro-Par 2003 Parallel Processing: 9th International Euro-Par Conference Klagenfurt, Austria, Aug. 26-29, 2003 Proceedings).
These techniques allow a user to use a mobile terminal while moving and to continue the communication using a stationary terminal superior in functionality and operability while staying at home or office.
However, in the above-described conventional techniques, a mobile terminal determines a transfer-destination terminal only on the basis of the information on the services and functions of a nearby terminal, acquired from the nearby terminal. Accordingly, a mobile terminal, when actually switching a terminal, may fail to connect a transfer-destination terminal to a communication-destination terminal and needs to try the process again, or may end up with connection undesirable for the user. Such problems include the following cases. That is, network-level connection between a transfer-destination terminal and communication-destination terminal fails due to security-related restrictions in the communication-destination terminal or the network; communication with the same quality as heretofore is not available due to a deficient band of the communication network between a transfer-destination terminal and a communication-destination terminal; and connection between applications fails due to different implementation in spite that a transfer-destination terminal and a communication-destination terminal have the same application-layer protocol. If such circumstances occur, a mobile terminal needs to transfer the session in search for an available transfer-destination terminal again, which is extra operation. Consequently, the user undesirably needs to wait longer until a process for switching to a transfer-destination terminal completes.